Treaty verification regimes rely on tamper-indicating technologies to maintain continuity of knowledge in between inspections. These technologies must indicate that tamper into equipment enclosures, material containers, or other items of interest has occurred, and indicate evidence of attempted repair. We are developing a novel and unique sensing concept based on the visual color change of polydiacetylene (PDA) materials that will indicate tamper and respond uniquely to multiple attack methods, including thermal, mechanical, solvent, and acid/base attack vectors. These materials benefit treaty verification regimes as well as other applications that require sensing phenomena or efficient and accurate indication of tampering. Diacetylene (DA) monomers have a structure similar to lipids, with a customizable chemical headgroup and a long carbon-based tail. In the polymerized form, intramolecular interactions with neighboring headgroups, and how those headgroups interact with other molecules during solventbased attacks, dictate the quantitative color changes and reversibility. Typically, literature has shown how specific PDA systems react for some types of stimuli, but no R&D has been performed evaluating how a PDA responds to all types of stimuli, which could be utilized for improved tamper indication. At a qualitative level an inspector could easily differentiate an attacked PDA system from an intact version due to the blue-to-red transition. The more-detailed color change would be verified via red-green-blue (RGB) analysis post-mortem to better understand the attack methodology. This talk will highlight the preparation, processing, and characterization of PDA materials and their associated colorimetric response to select stimuli relevant to tamper. Results on color variability, response repeatability, and principal component analysis (PCA), will also be discussed, as this is something that typically lacks in the current chemistry-base literature.
Year
2024
Abstract